This invention refers to a micronizing device and a method for micronizing solid particles fluidized in a pressurized power gas.
All industrial fields from medical industry to mine and building material industry use as raw materials a continuously increasing amount of different types of finely ground or micronized powder like dry products. The micronizing/fine-grinding of these products is nowadays generally carried out in jet mills, in which highly pressurized air or overheated water vapor is generally used as grinding energy. Depending on the final product and the fineness thereof tho energy consumption of these grinding and classifying processes is about 100 to 3000 kWh/ton.
An effective and relatively economical micronizing method is a technique operating according to the opposed jet mill principle. The opposed jet mill technique was developed during the 1980:ies and the 1990:ies substantially by the Finnish company Oy Finnpulva Ab, by means of which technique the energy economy and the grinding effectiveness of the fine grinding have been improved considerably. However, a wider utilization and application of the developed opposed jet mill technique has been considerably disturbed by the lack of effective auxiliary techniques applicable in connection with that technique and/or their low efficiency and high energy costs.
In fine-grinding/micronizing a high-energy power gas, most often pressurized air, is used as grinding energy. The micronizing devices will need industrial compressor effects ranging from 100 kw to 1000 kW depending upon application.
A drawback of previously known minronizing devices and methods is the considerably increasing energy consumption if the counter jet mill is adjusted to concentrate the grinding to eliminate particles having a particle size over 10 .mu.m. Further the pressure of the power gas has to be considerably high because an elevated pressure must be maintained in the jet mill in order to force the ground solid-gas suspension to a classifier and further treatment steps.
It is, therefore, an object of the present invention to eliminate the above drawbacks by providing a new and improved micronizing device.
It is another object of the present invention to provide a new and improved method for micronizing solid particles fluidized in a pressurized power gas having no one of the above drawbacks.